SiC single crystal sublimation growth apparatus

Abstract

A physical vapor transport growth system includes a growth chamber charged with SiC source material and a SiC seed crystal in spaced relation and an envelope that is at least partially gas-permeable disposed in the growth chamber. The envelope separates the growth chamber into a source compartment that includes the SiC source material and a crystallization compartment that includes the SiC seed crystal. The envelope is formed of a material that is reactive to vapor generated during sublimation growth of a SiC single crystal on the SiC seed crystal in the crystallization compartment to produce C-bearing vapor that acts as an additional source of C during the growth of the SiC single crystal on the SiC seed crystal.

The invention claimed is: 
     
       1. A physical vapor transport growth system comprising:
 a growth chamber charged with SiC source material and a SiC seed crystal in spaced relation; and 
 an envelope that is at least partially gas-permeable disposed in the growth chamber and separating the growth chamber into a source compartment that includes the SiC source material and a crystallization compartment that includes the SiC seed crystal, said gas-permeable envelope formed of a material that is reactive to vapor generated by sublimation growth of a SiC single crystal on the SiC seed crystal in the crystallization compartment, wherein said gas-permeable envelope is positioned in the growth chamber such that the vapor generated by sublimation growth reacts with the material forming the envelope to produce a carbon-bearing vapor that acts as an additional source of carbon during the growth of the SiC single crystal on the SiC seed crystal; 
 wherein the envelope is comprised of: a sleeve that surrounds sides of the SiC seed crystal and the growing SiC single crystal; and a gas-permeable membrane disposed between the SiC source material and a surface of the SiC seed crystal that faces the SiC source material; 
 wherein the gas-permeable membrane is made of porous graphite having a density between 0.6 and 1.4 g/cm 3  and a porosity between 30% and 70%; 
 wherein the graphite forming the gas-permeable membrane is comprised of graphite grains, each of which has a maximum dimension between 100 and 500 microns; and 
 wherein the gas-permeable membrane is disposed between 15 mm and 35 mm from the surface of the SiC seed crystal that faces the SiC source material. 
 
     
     
       2. The system of  claim 1 , wherein the sleeve is disposed between 0.5 mm and 5 mm from sides of the SiC seed crystal and the growing SiC single crystal. 
     
     
       3. The system of  claim 1 , wherein the gas-permeable membrane has a thickness between 3 mm and 12 mm. 
     
     
       4. The system of  claim 1 , wherein the sleeve has a wall thickness between 4 mm and 15 mm. 
     
     
       5. The system of  claim 1 , wherein the sleeve is cylindrical and the membrane is disposed at one end of the sleeve. 
     
     
       6. A physical vapor transport growth system comprising:
 a growth chamber charged with SiC source material and a SiC seed crystal in spaced relation; and 
 an envelope that is at least partially gas-permeable disposed in the growth chamber and separating the growth chamber into a source compartment that includes the SiC source material and a crystallization compartment that includes the SiC seed crystal, said gas-permeable envelope formed of a material that is reactive to vapor generated by sublimation growth of a SiC single crystal on the SiC seed crystal in the crystallization compartment, wherein said gas-permeable envelope is positioned in the growth chamber such that the vapor generated by sublimation growth reacts with the material forming the envelope to produce a carbon-bearing vapor that acts as an additional source of carbon during the growth of the SiC single crystal on the SiC seed crystal; 
 wherein the envelope is comprised of: a sleeve that surrounds sides of the SiC seed crystal and the growing SiC single crystal; and a gas-permeable membrane disposed between the SiC source material and a surface of the SiC seed crystal that faces the SiC source material; 
 wherein the gas-permeable membrane is made of porous graphite having a density between 0.6 and 1.4 g/cm 3  and a porosity between 30% and 70%; and 
 wherein the graphite forming the gas-permeable membrane is comprised of graphite grains, each of which has a maximum dimension between 100 and 500 microns. 
 
     
     
       7. The system of  claim 6 , wherein the sleeve is disposed between 0.5 mm and 5 mm from sides of the SiC seed crystal and the growing SiC single crystal. 
     
     
       8. The system of  claim 6 , wherein the gas-permeable membrane has a thickness between 3 mm and 12 mm. 
     
     
       9. The system of  claim 6 , wherein the sleeve has a wall thickness between 4 mm and 15 mm. 
     
     
       10. The system of  claim 6 , wherein the sleeve is cylindrical and the membrane is disposed at one end of the sleeve.